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Finding the Fourth Proportional to 120.77, 181.05 and 86.57

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Solution

The fourth proportional to 120.77, 181.05 and 86.57 is: 129.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.77 : 181.05 = 86.57 : x
  2. Step 2: Convert to fraction form
    120.77/181.05 = 86.57/x
  3. Step 3: Cross multiply
    120.77x = 181.05 × 86.57
  4. Step 4: Simplify right side
    120.77x = 15,673.50
  5. Step 5: Solve for x
    x = 15,673.50/120.77
  6. Step 6: Final answer
    x = 129.78

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.